finiteStateMachine

#include <sstream>

#include "FiniteStateMachine.h"

using namespace std;

const TokenType FiniteStateMachine::stateToTokenTable[NUM_STATE] = {
    /*state 0*/     T_NO_TYPE,
    /*state 1*/     T_NO_TYPE,
    /*state 2*/     T_ID,
    /*state 3*/     T_IF,
    /*state 4*/     T_ID,
    /*state 5*/     T_ID,
    /*state 6*/     T_ID,
    /*state 7*/     T_THEN,
    /*state 8*/     T_ID,
    /*state 9*/     T_ID,
    /*state A*/     T_ID,
    /*state B*/     T_ELSE,
    /*state C*/     T_ID,
    /*state D*/     T_MINUS,
    /*state E*/     T_PLUS,
    /*state F*/     T_EQ,
    /*state G*/     T_SEMI,
    /*state H*/     T_WHITE_SPACE,
    /*state I*/     T_ERROR,
    /*state J*/     T_NUM,
    /*state K*/     T_REAL,
    /*state L*/     T_COMMENT,
    /*state M*/     T_EQEQ,
    ////////////////
    /*state N*/     T_ID,
    /*state O*/     T_ID,
    /*state P*/     T_DEC,
    /////////////
};

const char FiniteStateMachine::supportedCharacters[NUM_OF_CHARACTERS] =
{
    '0','1','2','3','4','5','6','7','8','9',
    'a','b','c','d','e','f','g','h','i','j','k','l','m','n','o','p','q','r','s','t','u','v','w','x','y','z',
    '.','-',' ','\t','\n','\r',';','=','+','#'
};

/*
    S - space,
    T - tab,
    E - enter,
    C - clear line
*/
const int FiniteStateMachine::stateMatrix[NUM_STATE][NUM_OF_CHARACTERS] =
{
                // 0 1 2 3 4 5 6 7 8 9 a b c d e f g h i j k l m n o p q r s t u v w x y z . - S T E C ; = + #
    /* state 0 */ {0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0},        // IDLE_STATE

    /* state 1 */ {J,J,J,J,J,J,J,J,J,J,C,C,C,N,8,C,C,C,2,C,C,C,C,C,C,C,C,C,C,4,C,C,C,C,C,C,K,D,H,H,H,H,G,F,E,R},        // START_STATE

    /* state 2 */ {C,C,C,C,C,C,C,C,C,C,C,C,C,C,C,3,C,C,C,C,C,C,C,C,C,C,C,C,C,C,C,C,C,C,C,C,I,0,0,0,0,0,0,0,0,0},
    /* state 3 */ {C,C,C,C,C,C,C,C,C,C,C,C,C,C,C,C,C,C,C,C,C,C,C,C,C,C,C,C,C,C,C,C,C,C,C,C,I,0,0,0,0,0,0,0,0,0},        // T_IF

                // 0 1 2 3 4 5 6 7 8 9 a b c d e f g h i j k l m n o p q r s t u v w x y z . - S T E C ; = + #
    /* state 4 */ {C,C,C,C,C,C,C,C,C,C,C,C,C,C,C,C,C,5,C,C,C,C,C,C,C,C,C,C,C,C,C,C,C,C,C,C,I,0,0,0,0,0,0,0,0,0},
    /* state 5 */ {C,C,C,C,C,C,C,C,C,C,C,C,C,C,6,C,C,C,C,C,C,C,C,C,C,C,C,C,C,C,C,C,C,C,C,C,I,0,0,0,0,0,0,0,0,0},
    /* state 6 */ {C,C,C,C,C,C,C,C,C,C,C,C,C,C,C,C,C,C,C,C,C,C,C,7,C,C,C,C,C,C,C,C,C,C,C,C,I,0,0,0,0,0,0,0,0,0},
    /* state 7 */ {C,C,C,C,C,C,C,C,C,C,C,C,C,C,C,C,C,C,C,C,C,C,C,C,C,C,C,C,C,C,C,C,C,C,C,C,I,0,0,0,0,0,0,0,0,0},        // T_THEN

                // 0 1 2 3 4 5 6 7 8 9 a b c d e f g h i j k l m n o p q r s t u v w x y z . - S T E C ; = + #
    /* state 8 */ {C,C,C,C,C,C,C,C,C,C,C,C,C,C,C,C,C,C,C,C,C,9,C,C,C,C,C,C,C,C,C,C,C,C,C,C,I,0,0,0,0,0,0,0,0,0},
    /* state 9 */ {C,C,C,C,C,C,C,C,C,C,C,C,C,C,C,C,C,C,C,C,C,C,C,C,C,C,C,C,A,C,C,C,C,C,C,C,I,0,0,0,0,0,0,0,0,0},
    /* state A */ {C,C,C,C,C,C,C,C,C,C,C,C,C,C,B,C,C,C,C,C,C,C,C,C,C,C,C,C,C,C,C,C,C,C,C,C,I,0,0,0,0,0,0,0,0,0},
    /* state B */ {C,C,C,C,C,C,C,C,C,C,C,C,C,C,C,C,C,C,C,C,C,C,C,C,C,C,C,C,C,C,C,C,C,C,C,C,I,0,0,0,0,0,0,0,0,0},        // T_ELSE

    /* state C */ {C,C,C,C,C,C,C,C,C,C,C,C,C,C,C,C,C,C,C,C,C,C,C,C,C,C,C,C,C,C,C,C,C,C,C,C,I,0,0,0,0,0,0,0,0,0},        // T_ID

    /* state D */ {0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,I,0,0,0,0,0,0,0,0},        // T_MINUS

    /* state E */ {0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,I,0},        // T_PLUS

    /* state F */ {0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,M,0,0},        // T_EQ

    /* state G */ {0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0},        // T_SEMI

    /* state H */ {0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,H,H,H,H,0,0,0,0},        // T_WHITE_SPACE

    /* state I */ {0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0},        // T_ERROR

    /* state J */ {J,J,J,J,J,J,J,J,J,J,I,I,I,I,I,I,I,I,I,I,I,I,I,I,I,I,I,I,I,I,I,I,I,I,I,I,K,0,0,0,0,0,0,0,0,0},        // T_NUM

    /* state K */ {K,K,K,K,K,K,K,K,K,K,I,I,I,I,I,I,I,I,I,I,I,I,I,I,I,I,I,I,I,I,I,I,I,I,I,I,I,0,0,0,0,0,0,0,0,0},        // T_REAL

    /* state L */ {R,R,R,R,R,R,R,R,R,R,R,R,R,R,R,R,R,R,R,R,R,R,R,R,R,R,R,R,R,R,R,R,R,R,R,R,R,R,R,R,0,0,R,R,R,R},        // T_COMMENT

    /* state M */ {0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0},        // T_EQEQ

                // 0 1 2 3 4 5 6 7 8 9 a b c d e f g h i j k l m n o p q r s t u v w x y z . - S T E C ; = + #
    /* state N */{ C,C,C,C,C,C,C,C,C,C,C,C,C,C,O,C,C,C,C,C,C,C,C,C,C,C,C,C,C,C,C,C,C,C,C,C,I,0,0,0,0,0,0,0,0,0 },       // T_ID
    /* state O */{ C,C,C,C,C,C,C,C,C,C,C,C,P,C,C,C,C,C,C,C,C,C,C,C,C,C,C,C,C,C,C,C,C,C,C,C,I,0,0,0,0,0,0,0,0,0 },       // T_ID
    /* state P */{ C,C,C,C,C,C,C,C,C,C,C,C,C,C,C,C,C,C,C,C,C,C,C,C,C,C,C,C,C,C,C,C,C,C,C,C,I,0,0,0,0,0,0,0,0,0 },       // T_DEC
};


TokenType FiniteStateMachine::getTokenType(int stateNumber)
{
    return stateToTokenTable[stateNumber];
}


void FiniteStateMachine::initStateMachine()
{
    for (int i = 0; i < NUM_STATE; i++)
    {
        map<char, int> stateTransitions;
        for (int j = 0; j < NUM_OF_CHARACTERS; j++)
        {
            stateTransitions[supportedCharacters[j]] = stateMatrix[i][j];
        }
        stateMachine[i] = stateTransitions;
    }
}


int FiniteStateMachine::getNextState(int currentState, char transitionLetter)
{
    STATE_MACHINE::iterator it = stateMachine.find(currentState);

    if (it == stateMachine.end())
    {
        string strCurrentState;
        stringstream ss;
        ss << currentState;
        ss >> strCurrentState;
        string errMessage = "\nEXCEPTION: currentState = " + strCurrentState + " is not a valid state!";
        throw runtime_error(errMessage.c_str());
    }

    map<char, int>::iterator cit = it->second.find(transitionLetter);

    if (cit == it->second.end())
    {
        return INVALID_STATE;
    }
    else
    {
        return cit->second;
    }
}